"The evidence suggests that leaving people in corridors in the emergency department and putting them in corridors because there's no treatment space to look after them does more harm than leaving stable patients in the back of an ambulance where there's someone to look after them," he said.

SA Health Minister John Hill has distanced himself from the doctor's comments, saying ramping is not departmental policy.

"I would think generally you would want to make sure that people who go to the emergency department are treated in the emergency department," he said.

"That's why we've expanded the capacity of the emergency department. There will be times when there are more people trying to get in than can be managed. That will happen anywhere."

The Ambulance Employees Association said it was nonsense to suggest leaving patients in ambulances could be safer than in hospital corridors.

Association secretary Phil Palmer said building work at Flinders had used a "flawed' design.

"This redevelopment is making it very, very difficult for patients to get in from the ambulance. When the surge in arrivals happens, [there are] corridors where the triage nurses can't eyeball all their patients," he said.

"I know in the Royal Adelaide occasionally people end up in the corridor but, you know what, they have equipment on trolleys, so they have oxygen, they have suction equipment, so they take the equipment to the patient."